Ecosystem Overfishing in the Ocean (2008)

Fisheries catches represent a net export of mass and energy that can no longer be used by trophic levels higher than those fished. Thus, exploitation implies a depletion of secondary production of higher trophic levels (here the production of mass and energy by herbivores and carnivores in the ecosystem) due to the removal of prey. The depletion of secondary
production due to the export of biomass and energy through catches was recently formulated as a proxy for evaluating the
ecosystem impacts of fishing–i.e., the level of ecosystem overfishing. Here we evaluate the historical and current risk of
ecosystem overfishing at a global scale by quantifying the depletion of secondary production using the best available
fisheries and ecological data (i.e., catch and primary production). Our results highlight an increasing trend in the number of
unsustainable fisheries (i.e., an increase in the risk of ecosystem overfishing) from the 1950s to the 2000s, and illustrate the
worldwide geographic expansion of overfishing. These results enable to assess when and where fishing became
unsustainable at the ecosystem level. At present, total catch per capita from Large Marine Ecosystems is at least twice the
value estimated to ensure fishing at moderate sustainable levels.

LME:LEARN project is managed by the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organisation (UNESCO), implemented by the United Nations Development Programme (UNDP) and funded by the Global Environment Facility (GEF)”.